Pulmonary thromboembolism in childhood leukemia: 8-years' experience in a pediatric hematology center.

PURPOSE: To assess the occurrence and possible causes of pulmonary thromboembolism (PTE) in children with hematologic malignancies evaluated in a single pediatric hematology center. PATIENTS AND METHODS: Four hundred fifty-two patients admitted for leukemia in different stages of disease were evaluated whenever they presented with PTE-related acute respiratory failure (ARF). Diagnosis was based on a perfusional lung scan and a digital pulmonary angiography in most cases. When necessary, patients with ARF were transferred to the pediatric intensive care unit (ICU) for cardiorespiratory monitoring and support. Thrombolytic treatment was usually performed with urokinase at a loading dose of 2,000 to 4,560 IU/kg as single bolus followed by 2,000 to 4,530 IU/kg/h for 12 to 42 hours. Before thrombolytic therapy was discontinued, heparin was started at a daily dose of 100 to 500 IU/kg as a continuous infusion and continued for 6 to 26 days. RESULTS: Twelve of 452 children developed 17 PTE episodes, which were resolved completely after appropriate therapy in 15 cases. Univariate analysis showed a statistical correlation between PTE and the diagnosis of acute myeloid leukemia (AML) (P < .001). No major bleeding was observed after thrombolytic treatment. CONCLUSION: Our findings indicate that PTE is not an extremely rare event in children with leukemia and should be ruled out when sudden tachypnea develops in patients with risk factors such as previous tumor lysis, central venous catheter (CVC) malfunction, coagulation abnormalities, and drug-induced pulmonary toxicity. Complete resolution of PTE may be obtained in a high proportion of cases with early diagnosis and proper treatment.

Pulmonary thromboembolism in leukaemic children undergoing bone marrow transplantation.

Of 67 leukaemic children transplanted in our BMT unit 3 presented with severe acute respiratory syndrome associated with pulmonary thromboembolism (PTE) as diagnosed by scintiscan and/or angiography in the first month after BMT. Intervention with continuous positive pressure ventilation, urokinase (loading dose, then continuous infusion for 12-18 h) and heparin (continuous infusion for an average of 10 days) has been carried out successfully in two cases. In conclusion, when evaluating patients undergoing BMT and developing early pulmonary complications, PTE must be considered. The pathogenesis of PTE is still difficult to ascertain but urokinase therapy may reduce early morbidity.